Spark plug having a gap which is automatically adjustable from without the engine



Nov. 24, 1964 1.T. GELARDI ETAL 3,158,775

SPARK PLUG HAVING A GAP WHICH IS AUTOMATICALLY ADJUSTABLE FROM WITHOUT THE ENGINE Filed April 19, 1962 INVENTORS .M55/2H 7: 'uzzp/ B Pause/ewa PMN/wsu@ FIG.2

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wird! United States Patent O Fice NO SPARK PLUG HAVING A GA? Wlli l AUT@ MATICALLY ABEUSTABLE FROM W'ECHUT THE ENGINE Joseph T. Geiardi, 65 Salisbury Road, Yonkers, NX., and Pellegrino Pisanieilo, 42526 Murdock Ave., Eronx, NSY., nssignors of one-half to Milton Katz, Reuben Spencer, and Louis Alfred lenwartz, all of New York, FLY.

Filed Apr. i9, 1952, Ser. No. @8,717 6 Claims. (Cl. S13- 125) The present invention relates, in general, to spark plugs and, in particular, to an adjustable spark plug.

It is an object of the present invention to provide a highly novel and eicient spark plug that will have a long lite.

It is another object of the present invention to provide a spark plug which can be cleaned and reset to close spark gap tolerance without the necessity for using special tools and without the necessity of removing the spark plug from the engine.

It is a further object of the present invention to provide means for checking engine perfomance to ascertain electrical malfunctioning by providing means to short individual spark plugs so as to cause the misring thereof for locating the point of malfunction in the electrical circuit of the engine.

Other and further objects and advantages of the present invention Will be readily apparent to one skilled in the art from a consideration of following speciiication taken in connection with the appended drawings.

In the drawings, which illustrate the best mode presently contemplated for carrying out the inventions:

FIGURE l is a vertical sectional view taken through a spark plug pursuant to the present invention;

FIGURE 2 is a fragmentary View similar to FIGURE 1 and illustrates the spark plug in another condition thereof;

FIGURE 3 is a view similar to FIGURE 2 and illustrates a further condition oi the spark plug; and

FIGURE 4 is a fragmentary detail view of FIGURE 3 on an enlarged scale.

Referring now to the drawings in detail there is shown a spark plug l0 pursuant to the present invention. rl`he spark plug is provided with a conventional stationary ground electrode i2 and, pursuant to an important inventive concept of t e present invention, with a movable electrode 14 which can be operated to adjust the spark gap 16 or to make contact with ground electrode 12, if desired.

As here shown the spark plug itl is provided with a hollow cylindrical steel body member wmch is externally threaded, as at 2li, so that it can be screwed into the engine cylinder casing. Body member i8 is provided with the ground electrode 12 which extends from the lower end thereof. The body member mounts a core 22 formed of a suitable insulating material, preferably a ceramic material. The exterior conformation of the core is complementary to the interior conformation of the member 1S, as best seen in ElGURE 1. The core is secured in position within the body member by means of a threaded bushing 24 which is threadedly engaged within the upper end of the body member. Copper seals 25 and 2S space the core from the body member and the bushing. The core 22 is provided with an axial bore 35 in which the movable electrode 14 is mounted both for rotary movement and for vertical reciprocation.

A hollow shell 32 is mounted at the upper end of the core 22. More speciiically, the shell is provided with an enlarged housing portion 34 which is seated at the upper end of the core Iand is provided also with a diametrically reduced depending portion 36 having a stepped conformation which is received in a complementary enlargement 3S of the axial bore 3l) so as to seat portion 36 within the core 22. An enlarged end iiange 40 provided on portion 3-6 and seated within a complementary recess 42 in the core retains the shell 32 against vertical displacement. The housing 34 mounts a coil spring 44 and lthe depending portion 36 mounts a sleeve 46 lthe upper end of which extends into the housing.

An assembly 43 for operating the movable electrode 14 is provided on the housing 34. As here shown, said assembly comprises a hollow plunger Sil, formed of a suitable metal, and adapted to be electrically connected to a wire not shown) extending from the engine distributor. At its upper end, the plunger is crimped, as at 52, to a metallic post 54 to prevent relative movement therebetween. The post is connected to said wire. At its lower end, the plunger is provided with a flange 56 and with an apertured closure 5S through which the electrode 14 extends for relative movement. The upper end of the housing 34 is rolled over, as at 69 to provide a detent for the iiange 55 whereby it is retained against movement outwardly of the housing. The spring 44 is disposed between the movable iiange 56 and a seat 62 deiined within the housing. A vertical groove or keyway 64 is provided within the plunger 4S and a key 56 provided at the upper end of electrode 14 extends into the keyway to provide for vertical movement of the electrode relating to the plunger and to prevent relative rotary movement therebetween. A coil spring 63 is seated between post 54 and the upper end of electrode i4. The plunger is provided with a plurality of resilient metallic fingers 70 which depend from the closure 5S thereof and are biased into resilient engagement with movable electrode 14. More specifically, the lingers are provided with gripping surface portions 72 adapted to firmly grip the electrode 14. Each iinger is provided with a shoulder 75 below the grip 72 and with an oblique end surface 74 which diverges from the axis oi the movable electrode.

FIGURE 1 illustrates a condition in which it is assumed that, as a result of usage, the spark gap 16 is larger than it should be for optimum engine eiliciency. in this condition of the spark plug, the electrode 14 is retained against movement relative to electrode 12 by the resilient lingers 76 and spring 44 retains the plunger 48 in its illustrated position. lf it is desired to engage the electrodes 12 and 14 for adjusting the gap, cleaning the electrodes or shorting the spark plug for test purposes, the post is depressed as shown in FIGURES 2 and 3. FIGURE 2 illustrates an intermediate position of the post and FIGURE 3 illustrates the fully depressed condition thereof. ln the position of the parts illustrated in FIGURE 2, the oblique end surfaces 74 of the fingers are riding over the upper end sleeve 4 6 so as to spread the lingers apart and disengage the gripping surfaces thereof from the movable electrode. Until said disengagement or` the fingers, the electrode 14 moves toward the electrode 3 2 as a result of the downward pressure on the plunger 48. Once the fingers disengage the elect-rode 14, the electrode moves down as a result of the downward pressure applied on the post 54 and transmitted through the spring 63, it being noted that there is suilicient clearance in the apertured closure 58 in the plunger to allow for free movement of the electrode therethrough. Continued downward pressure exerted on the post 54 results in the engagement oi the electrodes, as shown in FEGURE 3, lthe lingers 7i? being held in their fully open condition by the sleeve 46, The space 7S (FIG. 3) between flange 55 and the upper end 6@ of shell 32 represents the full distance of the downward travel of the plunger. With the electrodes engaged, the post 54 can be manually rotated so as to rotate electrode 14 to clean the confronting electrode surfaces by removing carbon deposits therein. Once the post 54 is released, :the com- 3 pressed. spring 44 will expand to return the plunger to the position thereof illustrated in FIGURE 1, the gripping surfaces 72 sliding off the sleeve 46 and engaging thev electrode 14 when Ythe plunger reaches .the position thereof illustrated in FIGURE 2. Once theringers grip the electrode, the latter will be carried out of engagement with the fixed electrode 12. The electrode le wiil now be moved away from elect-rode 14 for a distance which is equal` tothe `space 8G. (FIGURE 2) between nange 56 and the upper end 60 of shell 32. rIhe space is exactly equal to the spark gap 82 (FIGURE. 2) which is thedesired optimuml spark gap, said space beingA obtained Vat the spark gap S2 when the spring 44 has fully expanded to the .position thereof shown in FIGURE 1.

Consequently, it will be apparent that as a result in the delayed action in the upward movement ot the plunger uponrelease of post 54, which action commences when the grips engage the electrode, the adjusted spark gap is v Y always equal'Y togap 82 regardless of the size of the o rig- -inal spark gap 16 since the distance Si?, which determines the size of gap 82, is always fixed by the engagement of the grips with the electrode.

We Claim-z 1. A spark plug comprising insulation means mounting a'iirst electrode in iixed relation and a second elec- 4trode for movement relative to said iirst electrode, means for moving said second. electrode comprising gripping meansV in normally engaged relation with said second electrode andoperable to move said second electrode toward engagementV with said first electrode, spring means operableV from a relaxed to a stressed condition thereof in response to said operation of said gripping means, and means operable inresponse to the, return of said spring means to said relaxed condition thereof to space said second electrode a predetermined distance from said first electrode` to deiiney a predetermined spark gap therebetween.

2; A spark. gap as in claim l, said spacing means including lost motion means.

n 3. A spark gap as in claim 1, means operable to disengage'said gripping means from said second electrode prior to the engagement of said electrodes, and means to complete said electrode engagement after the disengagement of said gripping means and to complete the stressing of said spring means.

4. A spark gap as in claim V3, said spacing means comprising means to eiiect the re-engagement of said second electrode by said gripping means after a predetermined movement of said second electrode to disengage said iirst electrode.

5. A spark plug comprising insulation means, a first eiectrode xediy mounted by said insulation means, a sec- .Y

ond electrode mounted by said insulation means for movement relative to said iirst electrode, a housing provided on said insulation means, the lower end of said second electrode dening a spark gap with said first electrode, a hollow plunger mounted for movement relative to said housing, the upper end of said Isecond electrode extend.- ing through said housing intov said plunger, said second electrode being ayially movable relative to said plunger, irst normaliy stressed compression spring means interposed between said upper end and said plunger, second normally relaxed compression means stronger thanv said first compression means operable from the relaxed to a compressed condition thereof in response to depression of said plunger, gripping means normally gripping said second electrode and operable by said plunger to move said second electrode toward said iirst electrode, and

means to disengage said gripping means fromV said sec-v References Cited in the tile of this patent FOREIGN' PATENTS 172,069 Great Britain Dee. 6, 1921 Germany Apr. 11, 1906 Y 

1. A SPARK PLUG COMPRISING INSULATION MEANS MOUNTING A FIRST ELECTRODE IN FIXED RELATION AND A SECOND ELECTRODE FOR MOVEMENT RELATIVE TO SAID FIRST ELECTRODE, MEANS FOR MOVING SAID SECOND ELECTRODE COMPRISING GRIPPING MEANS IN NORMALLY ENGAGED RELATION WITH SAID SECOND ELECTRODE AND OPERABLE TO MOVE SAID SECOND ELECTRODE TOWARD ENGAGEMENT WITH SAID FIRST ELECTRODE, SPRING MEANS OPERABLE FROM A RELAXED TO A STRESSED CONDITION THEREOF IN RESPONSE TO SAID OPERATION OF SAID GRIPPING MEANS, AND MEANS OPERABLE IN RESPONSE TO THE RETURN OF SAID SPRING MEANS TO SAID RELAXED CONDITION THEREOF TO SPACE SAID SECOND ELECTRODE A PREDETERMINED DISTANCE FROM SAID FIRST ELECTRODE TO DEFINE A PREDETERMINED SPARK GAP THEREBETWEEN. 